Department of the Navy (USN and USMC) uses the DON Correspondence Manual, SECNAVINST 5216.5D. It’s a coffee table book alright.
Mmm-hm.
Using proper nouns is a subtle way of distinguishing who ‘our guys’ are (opposed to any sailor, foreign commercial or US government, or any soldier), and there’s a small psychological attachment to it. Proper nouns make things Important, see.